The current taken via the input terminals is converted to measurement voltages via shunts 1 and 2, smoothed by the hardware filter (first-order low-pass / cutoff frequency 500 Hz) and digitalized in the subsequent A/D converters.
The filter values configured in the software (refer to EcoStruxure Machine Expert - Safety, Safety Modules Parameters in the online help) are applied during digitalization in the A/D converter. The signals then pass through the three stages of digital signal processing. The safety-related analog input channels (data type SAFEINT) are constituted as the arithmetic mean value of the two individual signals. Also refer to channel diagnostics.
The validity of analog signals is represented by the associated status signals. These binary status signals (data type SAFEBOOL) must also be evaluated each time the analog signals are used. A binary status signal with the status FALSE indicates an invalid value in the analog signal. When this occurs, the analog signal is no longer permitted to be used for safety-related assessments.
A reset must be performed in order to leave an error state. For this, a valid signal must be received at the analog input for the duration of the I/O update time. The error can then be acknowledged by a rising edge of the signal SafeRelease0x0y.
An optional sensor power supply is available to provide power to the sensors. If the sensor is powered externally, then the 2-wire connection examples must be applied. Current measurement protects the internal module sensor power supply against overload.